Athlon Optics Cronus 8.5×42

I was given the opportunity to review the new Athlon Optics Cronus 8.5×42 binocular. For those that didn’t read my review of the Argos model, Athlon is a relatively new company staffed by a variety of individuals that had worked for Bushnell in recent years. These gentlemen had the idea that they could offer high quality optics directly to consumers at a very reasonable price. I was quite satisfied with what they were able to produce with the Argos lineup so I was curious what they could do with their flagship model.


Athlon Optics has 6 binocular lines and 2 spotting scope lines. Each line is geared for a specific level of performance for that particular price point. The Cronus offers all of the latest features. A list of them is below…..

E2ES System– Edge 2 Edge Sharpness system

E2ES System is a field flattening system that produces sharper, clearer images all the way from one lens edge to the other

ED Glass– High definition glass ED glass gives you an image with little or no chromatic fringe so the final result brings a clearer and sharper image to your eyes

ESP Dielectric Coating– Enhanced Spectral Prism Dielectric Coating ESP Dielectric Coating is a multi layer prism coating that reflects over 99% of the light to your eyes bringing you a clear, bright image that displays accurate color reproduction.

Lightweight Magnesium Chassis Magnesium chassis give you the strength of a metal chassis while reducing the weight as much as 35%

XPL Coating– Xtra Protective Layer coating XPL Coating gives you an extra protection on the exterior lenses from dirt, oil and scratches

Phase Corrected prisms Phase corrected prisms produce images that have better contrast, a higher resolution and better color reproduction

BaK4 prisms Bak-4 glass prisms reflect more light to your eyes which will give you brighter and sharper image.

Advanced FMC Advanced Fully Multi-Coated lenses gives you better light transmission to bring optimum brightness and true color across the entire light spectrum.

Locking Diopter Locking Diopter keeps the diopter adjustment knob from accidentally moving from the optimal setting

Long Eye Relief Long eye relief can be particularly important for eyeglass wearers because longer eye relief allows them to still see the entire field of view.

Close Focus Close focus is important for those who are nature observers and especially important if you are going to watch butterflies or insects

Twist Up Eyecups Twist up eyecups with intermediate stops allow you to set the eyecups to the ideal eye relief for you eyes

Waterproof Waterproof to protects the binocular in the harshest weather conditions or if accidentally submerged underwater

Argon Purged Argon purging gives you better waterproofing and thermal stability


Advertised specifications are as follows:





FIELD OF VIEW FEET @1000 Yards 399 ft


CLOSE FOCUS 2 m /6.6 ft


WEIGHT 33 oz

When reviewing these features what jumped out at me initially was the mention of a field flattening element in the design. For those of you that are familiar with the market the use of field flatteners, typically in the eyepiece, has been utilized for quite some time but only in certain models and never in any great variety. That seems to have changed over the last three or four years.

Several of these most recently introduced models appear to be based off the same basic design as they all sport practically identical performance parameters and specifications (eye relief, field of view, physical weight, etc…). The latest introduction into this market segment is the Athlon Cronus. In many ways it appears to be based off the same base design but with one notable difference. All of the other recent introductions are offered in an 8×42 and a 10×42. Athlon decided to spice things up a bit by offering their Cronus model in both a 10×42 and an 8.5×42.

So you might ask why an 8.5x model? Well, Swarovski, and Swift, have had considerable success with this magnification. 8.5x does provide just a little bit more potential resolution when all else is equal. I have owned the original Swarovski EL 8.5×42, a vintage Swift Audubon of this configuration and a Bresser Montana 8.5×45. In each case I could see just a bit more detail with these 8.5x models than I could with my old standby 8x binoculars. Furthermore, I do not seem to notice much of the negatives of jumping up to a 10x model in the sense of notable decreased depth of field or notably narrower field of view. 8.5x seems like a worthwhile compromise for those looking for just a little more “reach” than an 8x can provide. With that being said, let us take a look at the rest of this binoculars’ optical performance.


Optical Performance:

The use of ED glass in the objective design, the field flattener in the eyepiece and the eyepiece design in general produce a very bright, sharp, contrast-filled image that does come very close to edge to edge sharpness. It is better than average in all of these areas plus it has relatively low levels of chromatic aberration (color fringing). So, its performance basically mirrors that of the previous models built on this platform. Where it is slightly better is in the level of apparent sharpness on axis. I believe the extra .5x magnification does provide slightly more detail particularly in the center of the field of view. I can see the smallest details relatively easily with this model.

The only negative aspect of this binoculars’ optical performance is that it does suffer from slightly increased angular magnification distortion and the subsequent rolling ball as a result. The field of view is flat with excellent edge sharpness but the transition zone between the on axis and off axis performance is slightly larger than in the 8x versions and also slightly more pronounced. With a static image the distortion is practically unnoticeable but when panning I pick up on it relatively easily.

Apparent brightness is above average as is the contrast level. Color representation is neutral to ever so slightly warm.

cronus5Phonescoped image with Cronus 8.5×42 via the Iphone 6S and Phone Skope adapter. Edited only by cropping to eliminate vignetting.

Mechanics and Ergonomics:

The build quality on this binocular is very good. I had no concerns with the central hinge tension or eyecup design and function. Internally the binocular is extremely clean, well baffled and blackened. The focusing knob is a little stiffer than I would prefer right out of the box but has loosened up somewhat over the last month. The minimum close focusing distance for my eyes was measured at 5.75 feet. The focusing speed is fairly fast in going from close focus to infinity in just a hair over one full turn of the focus knob. The diopter adjustment is located on the focusing knob and has a small raised extension used for adjustments. It has a locking function that requires you to depress it before it will freely move from its set position.
Probably the only objectionable issue with this model, as it was with similar designs, is the physical weight. The manufacturer lists a 33 oz weight which I tend to believe though I haven’t had a chance to weigh the binocular myself. This is about 5 ounces heavier than the previous model I reviewed and I believe that the increase is the result of thicker rubber armor. Personally, I don’t have an issue with the weight as I have used heavier binoculars in the past (Nikon Venturer LXL 8×42 – 36 oz, Vixen Foresta 7×50 – 31 oz, Leica Trinovid BN – 31 oz, Meopta Meostar 8×42 – 32 oz) but it might be a consideration for some folks looking for a lightweight full-sized design.



All in all this is another excellent introduction at/around $500. You receive all of the latest features available on models at a much more expensive price point. It sets itself apart from similarly designed models by offering an extra .5x magnification and a diopter adjustment on the central focusing knob. Build quality is very good and the binoculars are well balanced. Athlon definitely chose an excellent design to use as their flagship model